We have recently picked up the service on 3 Autec vacuum coolers at a mushroom farm. One system has been giving grief and not performing and is running a lower suction than the others at 1.5 bar instead of around 3 bar on r404a. Motor amps are lower at 20A instead of 25A yet the superheat is low and obviously the coil is filling but it seems as if there’s a restriction in the liquid supply into the evaporator. New drier, no suction filter, short pipe run, static coil, new TEV, no MOP function, Alco replaced with Danfoss TES5 & #2, but no improvement.
It’s a basic fridge circuit with no clever valves or bypass line though the electrical controls side is extensive but when it calls to run it’s just not doing the duty it used to.

I’m open to any suggestions...

Bitzer 4G-30.2-40P, air cooled condenser. Vacuum side works as it always has.